Causes of Uveitis and Risk Factors

The causes of uveitis can be divided into infectious and non-infectious causes. 

Infectious causes: The most common infections that cause uveitis are tuberculosis, viral infections (especially the herpes viruses) and toxoplasmosis. Although nearly any type of infection can enter the eye and cause inflammation. Most patients with infectious uveitis do not have evidence of infection elsewhere in the body. This is a fascinating area for uveitis researchers but very intriguing for the patients, as it is hard to understand, how the infection could enter the eye without any obvious injury, and without causing any disease elsewhere in the body. Many of these infections can hide inside the eye for long periods, even after they have been cleared from the rest of the body.

Non-infectious causes: The other important (and generally more common) cause of uveitis are non-infectious conditions. Non-infectious does not necessarily mean autoimmune, rather it means that there is no detectable cause of infection. Some of the non-infectious conditions are associated with disease elsewhere in the body. Common examples are HLA-B27 uveitis, sarcoidosis and Behcet’s disease. HLA-B27 is a gene, commonly associated with uveitis, and early morning joint pain, typically in the lower back, which gets well once the patient starts moving around. Other non-infectious uveitis are limited to the eye, but may be recognized by specific patterns of inflammation, that help us plan the treatment.

The cause of uveitis (infectious or non-infectious) may not always be evident at first presentation in many patients. Such patients are called ‘undifferentiated’ and should be followed up carefully for development of new clinical signs or lab tests, that may help us in reaching the diagnosis.

Are people with autoimmune/ rheumatic conditions at greater risk?

Several rheumatic diseases in the body are associated with increased risk of uveitis, though they may not be necessarily autoimmune. The most common such disease is HLA-B27 associated uveitis, described above. Other common rheumatic conditions, such as rheumatoid arthritis or lupus, are rarely causes of uveitis, though these are commonly tested in patients with uveitis. 

Is Uveitis hereditary

A. Many forms of uveitis have a genetic basis, though to variable degrees. However, this does not necessarily mean that the uveitis would be hereditary. There is often a component of environmental factors, that leads to a multifactorial basis of the disease.